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Ordering the final events in yeast exocytosis
E Grote1, C M Carr, P J Novick
1Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut 06520, USA.
The Journal of Cell Biology
|October 19, 2000
Summary
Sec18p disassembles soluble N-ethylmaleimide-sensitive fusion protein (NSF) attachment protein receptor (SNARE) complexes on yeast exocytic membranes. This process is crucial for proper vesicle fusion and secretion, with Sec1p playing a role after SNARE complex assembly.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Soluble N-ethylmaleimide-sensitive fusion protein (NSF) attachment protein receptor (SNARE) complexes mediate membrane fusion in exocytosis.
- In yeast, SNARE complex assembly is a late event in the exocytic pathway.
Purpose of the Study:
- To elucidate the function of Sec18p in SNARE complex dynamics during yeast exocytosis.
- To investigate the role of Sec1p in relation to SNARE complex assembly and function.
Main Methods:
- Analysis of SNARE complex assembly in yeast mutants (sec1-1, sec18-1).
- Assessment of Sec1p localization to sites of secretion.
- Investigation of secretory vesicle delivery and tethering.
Main Results:
- Mutations blocking vesicle delivery or tethering inhibited SNARE complex assembly and Sec1p localization.
- Sec1p was found to function after SNARE complex assembly.
- Sec18p was identified to disassemble SNARE complexes on the postfusion membrane, as evidenced by cis-SNARE complex accumulation in sec18-1 mutants.
Conclusions:
- Sec18p is essential for the disassembly of SNARE complexes on the postfusion membrane, a critical step for recycling SNAREs.
- Sec1p acts downstream of SNARE complex assembly, potentially regulating the fusion process or downstream events.